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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

Posted on 3 May 2010 by Ron Crouch

Guest post by Ron Crouch

Recently it was reported in the press (here and here) that researchers working at an automated weather station named Isachen on Ellef Ringnes Island, Nunavut, Canada experienced a brief rain shower over the weekend of April 24/25. Now according to David Phillips, the senior climatologist with Environment Canada, this is nothing short of bizarre. Environment Canada statistics show the earliest recorded rainfall in the High Arctic as occurring at Alert on May 21,1988, and the earliest recorded rainfall at Isachen was on June 7, 1975.

So it was put to me on a discussion board that I frequent that over the past 50 to 60 years there was both a lack of stations in the Arctic, and that the population was too sparse to make such wild claims of bizarre rainfall events. Now I'm no Nobel Peace Prize winner, nor do I receive research grants. In fact I'm not employed in the scientific or political arenas. I'm just a reasonably well read average Joe with an average Joe job, but I don't take things at face value either. So I ask as well: "Is the claim of rain in the High Arctic in April being bizarre reasonable or not?"

So I took it upon myself to do a little research of my own. I discovered that between 1840 and 2010 that there have been 168 weather stations in Nunavut. For the 2010 season there are currently 77 stations on line. Perhaps not very many by some standards but certainly enough to give adequate coverage of the region.

For my sampling I chose two Canadian stations and one in Greenland that are all in the same basic geographic area. They are as follows: Eureka on Ellesmere Island, Resolute on Cornwallis Island, and Thule A. B. I chose these three due to the fact that the former two have contiguous records from 1948 while the later has contiguous records from 1952. I further restricted my records search to the month of April.

Now what I discovered was that Eureka has never had so much as a trace of rain over the course of it's records in the month of April. Both Resolute and Thule have a prior history of trace amounts of rainfall in April over the course of their records. After a somewhat boring evening going through the records I found that Resolute had it's first recorded rainfall in April with any measurable amount on April 15, 2010, and subject to further verification stands at 4 mm (upon verification it will be the earliest recorded rainfall in the Canadian High Arctic breaking the old record by more than a month). This is the first and only measurable rainfall that Resolute has ever recorded in April. Now insofar as Thule is concerned their first and only measurable rainfall for April came on April 6, 2008 and racked up a grand total of .25 mm.

So yes the claim that rain in the Canadian High Arctic in April is bizarre -- isreasonable.

In the off chance that some reader goes off the deep end with a wild claim that this is empirical evidence in support of Global Climate Change, may I remind them that these are one off events and only speak to the oddity of the event itself. However I must agree with the postulations that in a warming world that these types of events may become more commonplace.

Your last paragraph is well stated. If rain in April starts to be commonplace in these places, that would be empirical evidence for climate change. A single bizarre event, by itself, can be consistent with what is expected from climate change. But you can never be certain that a single bizarre event is really due to climate change, even if climate change makes it more probable.

Several weeks ago, I was enticed into an email "debate" with a AGW "skeptic" who argued that because February, 2010 was the first February on record when there were no tornadoes in the United States, this demonstrated (somehow?) that AGW wasn’t happening. I can’t say I understood his reasoning (if there was any!), but the question raised the issue of the distinction between "weather" and "climate". In this regard, it's best to conform to standard definitions, as appear below in my (overly-long!) post.

As shown in the reply by RSVP @#2, using statistically rare "extreme weather events", or even more protracted "extreme climate events" to draw inferences regarding climate change is fertile ground for "cherry picking", and for this reason is best avoided. It is a "double edged sword" to use single events as providing proof that AGW is occurring, when certain other rare "events" such as this past cold, snowy winter in the eastern U.S. could potentially be cited as proof that AGW is a "hoax". Ultimately, climate is a statistical phenomenon. In this regard, single events can be measured in terms of their statistical likelihood, as has been done here. They do not, however, in and of themselves, describe climate, nor climate change, no matter how "bizarre" they may be.

The recent flap over whether there has been statistically significant warming in the U.K. since 1995 demonstrates that even multi-year trends can be used to prop up invalid conclusions, if one approaches the topic of climate change with a biased agenda.

"Climate":
Climate in a narrow sense is usually defined as the average weather, or more rigorously, as the statistical description in terms of the mean and variability of relevant quantities over a period of time ranging from months to thousands or millions of years. The classical period for averaging these variables is 30 years, as defined by the World Meteorological Organization. The relevant quantities are most often surface variables such as temperature, precipitation and wind. Climate in a wider sense is the state, including a statistical description, of the climate system. In various chapters in this report different averaging periods, such as a period of 20 years, are also used.

"Extreme Weather Event" AND "Extreme Climate Event":
An extreme weather event is an event that is rare at a particular place and time of year. Definitions of rare vary, but an extreme weather event would normally be as rare as or rarer than the 10th or 90th percentile of the observed probability density function. By definition, the characteristics of what is called extreme weather may vary from place to place in an absolute sense. Single extreme events cannot be simply and directly attributed to anthropogenic climate change, as there is always a finite chance the event in question might have occurred naturally. When a pattern of extreme weather persists for some time, such as a season, it may be classed as an extreme climate event, especially if it yields an average or total that is itself extreme (e.g., drought or heavy rainfall over a season).

"Climate change"
Climate change refers to a change in the state of the climate that can be identified (e.g., by using statistical tests) by changes in the mean and/or the variability of its properties, and that persists for an extended period, typically decades or longer... [the definition continues, but the latter parts are not relevant here.]

Most parts of Canada had an exceptionally mild winter earlier this year. Witness the winter Oympics near washout in Vancouver. It was 25°C on April 2 in my area (Toronto) – the normal is 8°C for that date. That blew away the previous record of 20.6°C in 1967. Incidentally, I wore my winter coat only two days this past winter, unlike every day the previous winter. This anomalous weather must be credited to the recent El Niño, since global warming stopped a while ago according to skeptics.

I was fortunate, as a 19-year-old, to get a job in the Canadian High Arctic (as an assistant carpenter/plumbers/electrician's helper).

Yes that meant I visited places like Eureka, Resolute, Mould Bay, and Alert (Weather Station Isaachsen had already been closed by that time). Sighting narwhals from the air (thank you De Havilland Canada for building the incomparable twin otter) was fun. Encountering a polar bear on the ground (me carrying no gun and hiking alone and therefore illustrating the stupidity of my youth) was not. But seeing thousands of nesting murres, or the occasional snowy owl or snow bunting. That experience drove me towards a lifelong pursuit of ecology.

Recently I have returned to the arctic, where I consistently see, and hear, from aboriginal persons, hunters, ornithologists, and others: that trends are all congruent with what is expected or projected by climate models.

John, you do a great service with this website, and the best part of it is to provide access to the primary literature that others might have a hard time finding.
If I had one request it would be to further synthesize some of the recent phenological papers. Thank you.

The overall picture for the last Spanish Winter doesn't suggest any particularly bizarre events.

In fact, the only unusual snow events occurred in A Coruña (Airport), Santander, Madrid (aerodrome of Cuatro Vientos), Toledo, Valencia (Manises airport) and Seville (Airport), where the number of days of precipitation in the form of snow surpassed the previous maximum values for January.

On checking those stations, though, you will notice that accurate readings only began in, respectively, 1971, 1945, 1982, 1966 and 1951. (I haven't included Santander because although readings began back in the 20s, it is still showing 1956 as the heaviest year).
Since most other places I have checked show a maximum snowfall around the 1930s or 50s, it can be perhaps claimed that the above stations may well have been higher then also, if only accurate readings had been taken at the time.

Just to prove I can do something as boring as you in the name of enlightenment I decided to have a look at some of those high Canadian records. I choose Eureka because from the map it looked like the closest to the site of this rain.

The max temp in Apr 2010 was -4.7oC (-5.2oC on the weekend in question). So I checked for some other 'high' temps in Apr at Eureka. Here's a few of the balmiest Apr days (year, day in Apr, temp oC)

(these are not all of them, just the warmest in a particular year and I reached my boredom threshold in the mid 80's)

While unusual it looks like the temps in 2010 aren't unique. It's a shame the records don't go back further because my understanding is that the 1930's and 1940's were a period of warmer arctic temperatures. Going through the record I noticed all forms of precipitation are rare in Eureka in Apr (average for whole of Apr is 3.5mm). Apr 2010 had 15mm of precipitation.

I won't profess to having had time to go through reams and reams of data but to my mind it is possible for all unique or rare or even bizarre events as being nothing more than pure fluke chances of something having happened.
Micro-climates exist all over the place. Here in North Oxfordshire we got a massive winter snowfall compared with the last 15 years that I can recall. Is that bizarre? Is that proof that AGW is not happening or is happening?
I firmly believe that we have influenced the natural cycles of climate change, which would normally take millennia to occur, by pumping out massive amounts of all manner of polluting gases (AGW gases) and it is obvious that the climate is warming from very basic evidence but I really despair when one-off events are even hinted at as evidence to prove or disprove what is a very obvious trend which is already being proven and is based on global scale, long term evidence. I reckon someone was fishing by putting out the bait and you were conscientious enough to want to genuinely want to answer in as honest a way as possible. However beware the origin of this item. They may seem all interested and curious on the outside but on the inside they are possibly looking for a fight. I bet they try to use some of your article to suggest something alternative and argumentative later on elsewhere. The sceptics are getting desperate for an argument that they can say disproves AGW and will dig as deep as is possible and use whatever tactic is readily available.
As the old saying tells us, 'There are lies, damn lies and statistics'.
The lists you quote are incontrovertible evidence but they prove nothing unless you try to say they do with some argument, no-matter how well founded, that shows reasonable proof of a pattern or trend. That's when the sceptics strike with counter evidence. Its all a silly game and as far as I am concerned its a waste of time. Lets just put down the charts and tables and get on with abandoning fossil fuels and start being realistic about the planets ability to sustain us as a species. AGW! Its happening. We need to prepare for the worst case scenario and no amount of tables and charts and nit-picking over micro details will stop it happening.
Have a nice day.
Kev C.

Re: CoalGeologist #4 wrote "It is a 'double edged sword' to use single events as providing proof that AGW is occurring, when certain other rare "events" such as this past cold, snowy winter in the eastern U.S. could potentially be cited as proof that AGW is a 'hoax'."

The Eastern U.S. this past winter may indeed be categorized as "snowy," but -- depending on how you categorize "Eastern U.S.," it is debatable to call it "cold" (or, more accuirately, "colder"). While Washington, D.C., had record snowfall totals from December through February, March recorded the forst time since record keeping began that the temperature did not drop below freezing (even overnight). I leave up to the scientists if increased precipitation is linked to a warming world. However, ceteris paribus, higher temperatures are.

So, I agree with coal geologists, and have found that the AGW-is-a-hoax crowd have ignored the temperature record int he evidence.

HumanityRules #7 Hail is formed in severe thunderstorms reaching great hight. The surface temperature has no more to do with this than creating the conditions that formed the thunderstorm to begin with, which may be 20,30 or 40 degrees C. Are we talking climate change?

I have to agree with CO2 (#14). Hail is formed by rising moisture in thunderheads that can sometimes reach over 50,000 feet high. Such storms only form in the presence of warm moist unstable air (summer). One would expect it to be warm at the surface when getting hail.

Now the Metar report you supplied for Pond Inlet for Apr 25, 1985 clearly states "fog,rain,snow" with an accumulation of .1 cm. The Environment Canada Daily and the Environment Canada Hourly records clearly indicate snow on that date with total precipitation registering .6 mm.

Moving on to Isachsen on June 7, 1975 The Metar report indicates fog with no accumulation of precipitation. On June 4, 1975 the Metar report does indicate "rain,snow" with no accumulation. So let's see what Environment Canada has to say about those dates on a daily basis. Well June 7 shows rain accumulation of .3 mm and June 4 shows the same with a trace of snow. So moving on to the hourly report for June 7 it indicates drizzle and fog throughout the day. Now on June 4 the hourly report indicates rain and snow changing to rain late in the evening. So yes the claim that June 7, 1975 being the first recorded rainfall at Isachsen is incorrect as it clearly took place three days earlier on June 4. So we'll have to give David Phillips at least an "E" for effort on that one.

Now for the final item which is May 1988 in Alert. The Metar record supplied shows a total of 4 cm precipitation for the month and shows no precipitation on the 21st and .1 cm on the 22nd. So what do the Environment Canada records say. Well it shows a .2 mm accumulation of rain on May 21 followed by a trace of rain on May 22.

So in conclusion, seeing that we are dealing with Canadian Climate Records then it is only appropriate when doing an analysis that we use the official Canadian documents from Environment Canada. Other than the small blurb that David had over June 7, 1975 for Isachsen, I'd say the climate record contentions are fairly spot on.

Interesting post and just goes to show that climate doesn't always fall into neat organized categories. In 1973 I was working in Uranium City in northern Saskatchewan (north shore of Lake Athabasca). At 8:00 pm on New Year's eve (73-74)it was -40 F (we hadn't switched to metric then). When we left the festivities at about 12:45 am New Year's day, the temperature had sored to +40F! By 10:00 am later that morning it had dropped to about - 10F.

I am sure there are many other oddities in the weather, especially in areas that are isolated as in Northern Canada, that go unreported. Certainly rain in April is not that far fetched - it may have happened 20 km away from the weather station in the past but simply went unreported.

Having worked in isolated areas of Canada in the past I can assure you that things such as thunder showers in winter happen, although not that frequently. Calgary (where I currently live) has had significant snow falls in August and golf weather in January, all which seem to be linked to where the jet stream is located.

I guess what this can tell us is climate and climate change is a multi-faceted process contingent not upon one single parameter but rather it is the result of the interaction of many parameters.

I had hoped to do this all in one post but there were some technical difficulties with the Environment Canada website.

#10 Berényi Péter

Your last point surrounding the Metar report for Alert on Apr 3, 2009. Although the Metar report clearly states rain with no accumulation it is unsupported by either hourly reports from Alert airport which only reports ice crystals, or Alert Autonomous which shows a trace of snow.

"It is a "double edged sword" to use single events as providing proof that AGW is occurring, when certain other rare "events" such as this past cold, snowy winter in the eastern U.S. could potentially be cited as proof that AGW is a "hoax"."

Without condoning citing single events as "proof" of AGW, I think the difference is that cold, snowy winters are consistent with AGW. While it may be an error to make too much of, say, a heat wave, it's an error of an entirely different type to claim that if it gets cold in the Northern Hemisphere in winter, then AGW must be a hoax. One results from confusion; the other is an attempt to produce it.

I've dealt with METARs a lot during my days as a pilot and flight instructor. They are automated reports from stations that rely on sensors. Pilots learn to not rely too extensively on reports from unmanned stations, especially for some indications. The station "looks" at a rather small extent of sky, so sky cover may be different from reality. Visibility is ground visibility (normally measured in a direction parallel to the runway axis from the station location) and may not be the same as the slant range visibility that matters when looking for the runway treshold in an instrument approach.

Some stations have a precipitation discriminator (type2 if I recall, it usually figures in the remark section of the aviation METAR), others don't. Even the ones that have it can experience temporary malfunctions of the sensor. Some types of precipitation are more likely to "confuse" the sensors, like heavy fog that falls as very fine drizzle (especially below freezing), or freezing rain.

The stations are a great tool, but they're only robots and ill-equipped to give an accurate rendition of what goes on in complex weather situations. You could have a cold layer near the ground just a couple of hundred feet thick, with layers of various and higher temperatures as altitude increases, leading to all sorts of variations in precipitation. What was described by Geo-Guy certainly reflects one of these types of situations evolving over time, seen from the ground. It's all weather.

I would not put too much trust in such minute amounts of precip as were reported in the METARs linked by John and other posters.

Arctic Oscillation, when very negative, as it was this past mid winter, produces extreme cold spells east of the Rockies, over Europe and eastern Asia. That’s exactly what we saw in January & February. The mild winter in most of Canada would be better explained by the the recent El Niño.

That 1 or 2 degree warmer area in the tropical Pacific has a long reach!

Or, from your link
"This [the positive phase of the AO] keeps much of the United States east of the Rocky Mountains warmer than normal, but leaves Greenland and Newfoundland colder than usual. Weather patterns in the negative phase are in general "opposite" to those of the positive phase, as illustrated below."

When the wind blows hard from the Arctic, the Arctic does not become a giant vacuum. Other, warmer air blows in from elsewhere. The slightly warmer air from the tropical Pacific, even if it gets there without cooling much, could not account for the very high arctic temperatures. What does it is the quantity of air from lower latitudes, which must match the quantity of air blowing out of the Arctic.

I had hoped that mentioning the AO would make a light bulb go off. How does it correlate with warm Arctic years in the past?

#24 - can you make your point differently? Are you saying warming arctic corresponds with negative AO? The opposite? Something different? A quick review shows that AO is not strongly correlated with temperature in 1999 and 2005 (notably hot years...).

It’s a regular pattern, at least in east central Canada. Each El Niño episode does give us very mild winters. And colder winters result when a La Niña episode is in effect (such as the prior two winters before this last one). So yes ENSO does have a long reach. Keep in mind that Toronto is slightly closer to the equator than to the North Pole, at the same latitude as southern France (but without the palm trees), so we get influenced by both ends.

Perhaps in the far north, the Arctic Oscillation normally dominates. I did notice that Canadian Arctic surface temperatures were significantly above normal, while at the same time the Canadian prairies and US plains states were freezing under the deepest part of the negative AO. There’s much supporting science that says the stratosphere above the Arctic warms during the negative phase of an AO but little science making such claims for surface temperatures. So I’m not prepared to say that a negative AO typically results in warmer Arctic surface temperatures.

Analyzing it logically, if the air pressure is high in the north and low in the mid latitudes (a negative AO), then what one should see is the surface air moving generally from north to south (from the high pressure area to the low pressure area). This in turn should pull down some upper atmosphere in the north to replace the exiting air, which in turn, pushes the higher level jet stream to move in the opposition direction to fill the high level void created in the north, and lifting air out of the south to complete the circle. These movements would all have a slight eastward slant due to planetary rotation. With colder high level air being pulled down in the north, one would expect things to be a bit cooler up north on the surface, and some minor ice extent recovery this past winter is evidence that this did happen overall.

But how does one explain the warm surface temperatures I noticed in the north at the peak of the negative AO? I don’t know but perhaps, with an El Niño raging on top of the usual GW and a negative AO, just maybe a layer of warm Pacific air was being pulled in below the north and east moving jet stream during that same time and it was filling the surface viod in the far north instead of higher air. Weather is very chaotic so it’s hard to say.

The early rainfalls reported in this article were well after the negative AO peak (but still within the ENSO influence), so we might have moved off topic by discussing AO here, but it was worth considering nonetheless.

Westwell:
Perhaps your reporter in the Hawaii story should have reported on ice in the great lakes last year, since they used data from last year. There was a lot of ice in the great lakes last year. It was a La Nina year. This year, in contrast, was record lows. Last year was high for recent years, but not record highs. It is easy to cherry pick data to try to influence people who are uninformed. You will have a lot more trouble on this site where people check what you say.

Sometimes an event such as the rain even here is spatially or temporally limited and of as such is an isolated weather event. If it coincides with other events spatially and temporally then it is just another measure of a broader event that is important. For example February had the 3rd highest mean snowcover extent of the last 44 years in North America according to the Rutgers Global Snow lab. The most extensive melt off of snowcover in the last 44 years has occurred in March and April. Leading to March mean snowcover extent being the 18th of 44 years, and April being the 41st highest of 44 years. That is correct going from third most to third least snowcover. This indicates a continent wide period of unusual melt conditions.